Standard and Steering Compasses
The Chief of Naval Operations requires that each self-propelled ship and
service craft of the United States Navy be equipped with one or more
magnetic compasses suitable for navigation.
Except for modern nuclear-powered submarines, all ships and craft,
regardless of size or classification, must have a magnetic steering
compass at the primary steering station.
Many ships carry more than one magnetic compass. The primary
magnetic compass is called the steering compass. It is normally located
on the centerline in the ships pilothouse (except aboard aircraft
carriers), where it can best be seen by the helmsman. The readings from
the steering compass are labeled "per steering compass" (PSTGC).
If a ship has two magnetic compasses, the second compass is called the
standard compass. The ships standard compass is normally located on
the ships centerline at the secondary conning station. The readings from
the standard compass are expressed as "per standard compass" (PSC).
The readings from the ships gyrocompass are "per gyrocompass"
(PGC). Courses and bearings by these compasses must be carefully
differentiated by the abbreviations.
A magnetic compass cannot be expected to give reliable service unless it
is properly installed and protected from disturbing magnetic influences.
Certain precautions must be observed in the vicinity of the magnetic
If possible, a compass should not be placed near iron or steel
equipment that will be moved frequently. Thus, a location near a
gun, boat davit, or boat crane is not desirable.
The immediate vicinity should be kept free of sources of magnetism,
particularly those of a changing nature.
When possible, no source of magnetism should be permitted within a
radius of several feet of the magnetic compass.